Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 11: Epitaxy and growth I

O 11.10: Vortrag

Montag, 27. März 2006, 17:15–17:30, WIL A317

Metastable and Stable Structures of In on W(110) — •Martin Gabl¹, Marek Trzciński², Norbert Memmel¹, Antoni Bukaluk², and Erminald Bertel¹ — ¹Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria — ²Institute of Mathematics and Physics, University of Technology and Agriculture, Pl-85796 Bydgoszcz, Poland

The growth of indium on W(110) at submonolayer coverages was studied by low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). At room temperature with increasing coverage three indium-induced overlayer structures - (3x1), (1x4) and (1x5) - are observed. The (3x1) structure corresponds to an overlayer with 1 atom/unit cell of the In-overlayer and an ideal coverage of 0.33 ML. The (1x4) structure is essentially interpreted as a Moire-pattern between the W(110) substrate and a slightly distorted In(111) layer in Nishiyama-Wassermann orientation. The atom density in the (1x4) overlayer matches that of a close-packed In(111) layer within 2%. The (1x5) structure is interpreted as a compressed monolayer, where the areal density of In exceeds that of an In(111) monolayer by 8%. Upon annealing or aging at room temperature the In atoms of the (3x1) structure agglomerate into islands with the high-coverage (1x4) structure. Hence the (3x1) structure - although being ordered - is only metastable. This transition can also be induced by exposure to oxygen. Obviously oxygen first adsorbs onto the free W(110) surface and compresses In atoms into densely-packed islands of (1x4) periodicity rather than oxidizing the indium adlayer.